The invention relates to a roller skate.
Roller skates with four rollers arranged in pairs as well as with several rollers arranged in series, so-called inliners, and with mixed forms are known.
The best-known ones are the four-wheel roller skates, that are generally equipped with four often relatively wide, usually cylindrical rollers with the same diameter. During travel such roller skates are placed on the road surface as a rule as horizontally as possible with all four rollers at the same time.
The shoes of these four-wheel roller skates, that comprise front and back rollers that can be guided to a limited extent, are relatively low in the heel area so that the user can bend his legs to both sides in the area above the ankle. This makes it possible, by virtue of the oblique position of his legs, to control the front and back rollers of four-wheel roller skates, which rollers can be guided to a limited extent. However, an oblique position of the roller skates is not possible or not readily possible.
U.S. Pat. No. 5,551,713 teaches a roller skate in which only the two back rollers are adjacent to one another as in the four-wheel roller skates but the two front rollers are arranged centrally and in series as in inliners. The back rollers are located far apart from one another and on the outside of the shoe and can be guided in a limited manner. Even this roller skate must be placed as horizontally as possible on the road surface during travel, that is, not in an oblique position as in the case of customary inliners. The guiding of the two rear rollers is difficult on account of the front rollers that are arranged in series but are inflexible so that a correct curve travel is hardly possible.
The guiding of the three-wheel roller skate, the so-called Dutch skate, that was put on the market in the 50s, is somewhat simpler. This skate has a large roller in front of the shoe and two equally large rollers that are, however, arranged on the sides of the shoe and extend upward above the shoe sole. However, even this shoe should be placed as horizontally as possible, that is, not in an oblique position, on the road surface.
U.S. Pat. No. 6,722,670 teaches a roller skate with a different shape that comprises three rollers arranged adjacent to each other on a front wheel axle and three on a back wheel axle, namely, a central, approximately cylindrical roller and two conically designed rollers located on the outside in each instance. These conical rollers should make an oblique position possible up to a certain inclination and prevent lateral slipping. However, during normal travel, e.g., over straight stretches, only the two central cylindrical rollers make contact with the ground whereas the outer, conical rollers, whose diameter is smaller than the diameter of the central rollers, do not touch the road surface. The roller skate rests on the road surface with four rollers only at a certain angle of inclination and curve travel is hardly possible. On the other hand, at a lesser angle of inclination this roller skate behaves like the known inliners.
The inliners that are very common today are equipped with rollers that are arranged centrally under the shoe sole and vertically in series.
Recently, a two-wheel inliner with overlarge, obliquely projecting rollers has come on the market that is like the one known from U.S. Pat. No. 5,951,028; U.S. Pat. No. 6,273,437 B1 and U.S. Pat. No. 6,443,464 B2. The oblique position of the rollers permits extreme oblique positions of the user as well as the use of larger rollers, given a good contact with the ground, since the latter can project laterally over the boot of the roller skate.
However, it is characteristic for all inliners that their serial rollers have exclusively a linear contact so that the travel with these inliners requires a not inconsiderable degree of skill, force and a good feeling of equilibrium.
This, it can be determined that, although in the meantime many millions of these inliners have been sold in past years to sportspersons of all age groups, a large part of these inliners are not being used or are no longer in use, probably on account of these problems.
It is difficult for a beginner to keep his balance on these inliners since he must constantly compensate transverse movements. This unaccustomed strain stresses the untrained feet, ankles, feet muscles and sinews of the user to a great extent.
Thus, it turned out that a satisfactory usage of these inliners is only possible for those persons who are well-trained and on the other hand have a good technical understanding or feeling for the progression of movement with inliners.